Interaction of inflammatory cells and oral microorganisms. II. Modulation of rabbit polymorphonuclear leukocyte hydrolase release by polysaccharides in response to Streptococcus mutans and Streptococcus sanguis.
The release of lysosomal hydrolases from polymorphonuclear leukocytes (PMNs) has been postulated in the pathogenesis of tissue injury in periodontal disease. In the present study, lysosomal enzyme release was monitored from rabbit peritoneal exudate PMNs exposed to Streptocccus mutans or Streptococcus sanguis. S. mutans grown in brain heart infusion (BHI) broth failed to promote significant PMN enzyme release. S. sanguis grown in BHI broth, although more effective than S. mutants, was a weak stimulus for promotion of PMN hydrolase release. Preincubation of washed, viable S. mutans in sucrose or in different-molecular-weight dextrans resulted in the ability of the organisms to provoke PMN release reactions. This effect could bot be demonstrated with boiled or trypsinized S. mutans or with viable S. sanguis. However, when grown in BHI broth supplemented with sucrose, but not with glucose, both S. mutans and S. sanguis triggered discharge of PMN enzymes. The mechanism(s) whereby dextran or sucrose modulates PMN-bacterial interaction may in some manner be related to promotion of microbial adhesiveness or aggregation by dextran and by bacterial synthesis of glucans from sucrose. (+info)
Survey of total error of precipitation and homogeneous HDL-cholesterol methods and simultaneous evaluation of lyophilized saccharose-containing candidate reference materials for HDL-cholesterol.
BACKGROUND: Standardization of HDL-cholesterol is needed for risk assessment. We assessed for the first time the accuracy of HDL-cholesterol testing in The Netherlands and evaluated 11 candidate reference materials (CRMs). METHODS: The total error (TE) of HDL-cholesterol measurements was assessed in native human sera by 25 Dutch clinical chemistry laboratories. Concomitantly, the suitability of lyophilized, saccharose-containing CRMs (n = 11) for HDL-cholesterol was evaluated. RESULTS: In the precipitation method group, which included 25 laboratories and four methods, the mean (minimum-maximum) TE was 11.5% (2.7-25.2%), signifying that 18 of 25 laboratories satisfied the TE goal of +info)
Purification and characterization of rat hippocampal CA3-dendritic spines associated with mossy fiber terminals.
We report a revised and improved isolation procedure for CA3-dendritic spines, most of them still in association with mossy fiber terminals resulting in a 7.5-fold enrichment over nuclei and a 29-fold enrichment over myelin. Additionally, red blood cells, medullated fibers, mitochondria and small synaptosomes were significantly depleted. We show by high resolution electron microscopy that this subcellular fraction contains numerous dendritic spines with a rich ultrastructure, e.g. an intact spine apparatus, membranous organelles, free and membrane-bound polyribosomes, endocytic structures and mitochondria. This improved experimental system will allow us to study aspects of post-synaptic functions at the biochemical and molecular level. (+info)
Site-directed mutagenesis of loop L3 of sucrose porin ScrY leads to changes in substrate selectivity.
The difference in substrate selectivity of the maltodextrin (LamB) and sucrose (ScrY) porins is attributed mainly to differences in loop L3, which is supposed to constrict the lumen of the pores. We show that even a single mutation (D201Y) in loop L3 leads to a narrowing of the substrate range of ScrY to that resembling LamB. In addition, we removed the putative N-terminal coiled-coil structure of ScrY and studied the effect of this deletion on sucrose transport. (+info)
Characterization of the divergent sacBK and sacAR operons, involved in sucrose utilization by Lactococcus lactis.
The divergently transcribed sacBK and sacAR operons, which are involved in the utilization of sucrose by Lactococcus lactis NZ9800, were examined by transcriptional and gene inactivation studies. Northern analyses of RNA isolated from cells grown at the expense of different carbon sources revealed three sucrose-inducible transcripts: one of 3.2 kb containing sacB and sacK, a second of 3.4 kb containing sacA and sacR, and a third of 1.8 kb containing only sacR. The inactivation of the sacR gene by replacement recombination resulted in the constitutive transcription of the sacBK and sacAR operons in the presence of different carbon sources, indicating that SacR acts as a repressor of transcription. (+info)
Oligofructose stimulates calcium absorption in adolescents.
BACKGROUND: In rats, nondigestible oligosaccharides stimulate calcium absorption. Recently, this effect was also found in human subjects. OBJECTIVE: The objective of the study was to investigate whether consumption of 15 g oligofructose/d stimulates calcium absorption in male adolescents. DESIGN: Twelve healthy, male adolescents aged 14-16 y received, for 9 d, 15 g oligofructose or sucrose (control treatment) daily over 3 main meals. The treatments were given according to a randomized, double-blind, crossover design, separated by a 19-d washout period. On the 8th day of each treatment period, 44Ca was given orally with a standard breakfast containing approximately 200 mg Ca. Within half an hour after administration of 44Ca, 48Ca was administered intravenously. Fractional calcium absorption was computed from the enrichment of 44Ca:43Ca and 48Ca:43Ca in 36-h urine samples, which was measured by inductively coupled plasma mass spectrometry. RESULTS: An increase in true fractional calcium absorption (%) was found after consumption of oligofructose (mean difference +/- SE of difference: 10.8+/-5.6; P < 0.05, one sided). The results are discussed in relation to the methods used. CONCLUSION: Fifteen grams of oligofructose per day stimulates fractional calcium absorption in male adolescents. (+info)
Rapid induction of functional and morphological continuity between severed ends of mammalian or earthworm myelinated axons.
The inability to rapidly restore the loss of function that results from severance (cutting or crushing) of PNS and CNS axons is a severe clinical problem. As a novel strategy to help alleviate this problem, we have developed in vitro procedures using Ca2+-free solutions of polyethylene glycol (PEG solutions), which within minutes induce functional and morphological continuity (PEG-induced fusion) between the cut or crushed ends of myelinated sciatic or spinal axons in rats. Using a PEG-based hydrogel that binds to connective tissue to provide mechanical strength at the lesion site and is nontoxic to nerve tissues in earthworms and mammals, we have also developed in vivo procedures that permanently maintain earthworm myelinated medial giant axons whose functional and morphological integrity has been restored by PEG-induced fusion after axonal severance. In all these in vitro or in vivo procedures, the success of PEG-induced fusion of sciatic or spinal axons and myelinated medial giant axons is measured by the restored conduction of action potentials through the lesion site, the presence of intact axonal profiles in electron micrographs taken at the lesion site, and/or the intra-axonal diffusion of fluorescent dyes across the lesion site. These and other data suggest that the application of polymeric fusiogens (such as our PEG solutions), possibly combined with a tissue adherent (such as our PEG hydrogels), could lead to in vivo treatments that rapidly and permanently repair cut or crushed axons in the PNS and CNS of adult mammals, including humans. (+info)
Stimulation of collagen galactosyltransferase and glucosyltransferase activities by lysophosphatidylcholine.
Lysophosphatidylcholine stimulated the activities of collagen galactosyl- and glucosyl-transferases in chick-embryo extract and its particulate fractions in vitro, whereas essentially no stimulation was noted in the high-speed supernatant, where the enzymes are soluble and membrane-free. The stimulatory effect of lysophosphatidylcholine was masked by 0.1% Triton X-100. In kinetic experiments lysophosphatidylcholine raised the maximum velocities with respect to the substrates and co-substrates, whereas no changes were observed in the apparant Km values. Phospholipase A preincubation of the chick-embryo extract resulted in stimulation of both transferase activities, probably gy generating lysophosphatides from endogenous phospholipids. No stimulation by lysophosphatidylcholine was found when tested with 500-fold-purified glycosyltransferase. The results suggest that collagen glycosyltransferases must be associated with the membrane structures of the cell in order to be stimulated by lysophosphatidylcholine. Lysophosphatidylcholine could have some regulatory significance in vivo, since its concentration in the cell is comparable with that which produced marked stimulation in vitro. (+info)